An organic electroluminescence (referred to herein as organic EL) display device is arranged with a light-emitting element in each pixel and displays an image by individually controlling the light emission. A light-emitting element includes a structure in which a layer (referred to herein as [light-emitting layer]) including an organic EL material is sandwiched between a pair of electrodes regarded as an anode electrode and cathode electrode. The organic EL display device is arranged with one electrode as a pixel electrode in each pixel, and the other electrode as a common electrode which extends over a plurality of pixels and is applied with a common voltage. The organic EL display device controls light emission from a pixel by applying the voltage of the pixel electrode to each pixel with respect to the voltage of the common electrode.
In recent years, a so-called transparent display is known in which the scene at the rear of a display region can be viewed through the display region. As a transparent display, a structure is known as is disclosed in Japanese Laid Open Patent No. 2014-049313 for example in which an emission region arranged with a light-emitting element which carries out image display, and a transparent region which includes a so-called see through structure is arranged separately to the emission region in each of a plurality of pixels arranged in a matrix form in a display region.
Generally, a plurality of thin film transistors or capacitors are arranged in a driving circuit of a light-emitting pixel which carries out image display and a fine layout design is required given the progress in high definition. However, in a transparent display including the structure described above, further limitations in the area taken up by an emission region are produced in order to secure a transparent region in each of a plurality of pixels and it becomes difficult to secure a sufficient area for arranging a storage capacitor in an emission region. When the size of a storage capacitor can not be sufficiently secured, the display device is easily affected by a variation in the characteristics of a thin film transistor and high image quality becomes difficult to achieve. That is, miniaturization of a pixel for high definition and high image quality of a display device are in a trade-off relationship.
On the other hand, with respect to a self light-emitting type organic EL display device, in a liquid crystal display device which displays an image by control of light from a backlight, a structure of a pixel for easily obtaining a high definition and/or high image quality display device by forming an auxiliary capacitor using a transparent electrode used in a liquid crystal element is known as is disclosed in Japanese Laid Open Patent No. H6-148684, Japanese Laid Open Patent No. H6-258669 and Japanese Laid Open Patent No. H10-78593 for example.
In consideration of the problems described above, the present invention aims to provide a structure of a new pixel using structural elements unique to a self light-emitting type display device which can achieve both high definition and high image quality even in a transparent display.